Fluorescent material and a fluorescent element incorporating the same



UNITED STATES PATENT OFFICE FLUORESCENT MATERIAL AND A FLUO- ISCESCENT ELEMENT INCORPORATING THE Carl Pfanstiehl. Highland Park, 111., asslgnor to Pfanstiehl Chemical Company, a corporation of Illinois No Drawing. Application November 23, 1938, Serial No. 242.107

Claims. (Cl. 25041) This invention relates to an improved fiuoresfusing of the particles, but interaction does occent material and a fluorescent element incorcurv The character of material so formed should porating the same. crumble readily between the fingers and require One of the most widely used fluorescent mateno grinding. The mixture of zinc silicate and 5 rials for incorporation with gaseous illuminating beryllium silicate will not stand as high temper- 5 elements such as neon or argon. combined with atures zinc sillcate alone and preferably the mercury vapor is zinc ortho-silicate. temperature should not exceed 2150 F.

In my copending application Serial No. 190,880. To this base an activator is added. In each filed February 16, 1938, is described a method for case, or course, the activator is added beiore the l preparing zinc ortho-sillcate in such manner as powder is formed and whenever it is here stated 1 to improve its fluorescent properties by producthat an activator or other material is added to lug individual unground crystals of the order of the base, it should be understood that it is added one micron in cross section. before formation, unless otherwise specifically The present invention is preferably carried out stated. in combination with the improvements therein When manganese is used as the activator, it is 15 set forth, the color of the fluorescent illuminapreferably employed in fairly large portions comtion being markedly changed by the production pared to the amount of manganese normally inof fine particles of that type. corporated for this purpose. The addition of In preparing the objects of the present 1nven- 6.1% of manganese gives a whitish light, but a tion, a base comprising roughly 1% molecules far from brilliant one. Preferably upwards of of zinc ortho-silicate to 1 molecule oi beryllium 0.4% is employed. The use of 0.4% to 0.5% of silicat is employed. manganese gives a whitish fluorescent illumina- With this is incorporated a minor Liiruiliiia'E- tion. The of 4% of manganese dioxide pro- 01 an activator, such as a manganese compound, duces an orange color and the use 01 6% produces preferably manganese dioxide, and in many cases, a rosy pink. g5 particularly those where a white light is desired, When manga e i incorporated. it 18 Preferred a further minor percentage of a rare earth metal. to use a lower temperature, the heat treatment A preferred 'Jase may be prepared by incorporatpreferably not going over 2100 F. The degree ing the following ingredients: of fluorescence increases as the manganese in- 39 Parts by weight creases, but the color becomes more reddish. 80

zno 50 685 However. if higher temperatures are employed, B60 91750 the fluorescence becomes less and the powders 565 pro uce a pink color even at the lower manganese contents. 3:; This base contains approximately 3.4 molecules In this connection, it should be pointed out of zinc ortho-silicate (ZnzSiOd to 2.2 molecules that the colors here described do not relate to of beryllium ortho-sillcate (13825104) the powders themselves, but the illumination they The ingredients are thoroughly and carefully produce under short wave radiation. mixed in a ball mill as described in my applica- Very much improved results are obtainable by 40 tion Serial No. 190,880. The materials are used the addition of a pair of activators instead of the 40 in the form of line powders and mixed with a sole use of manganese. For this Purp se any of liquid such as methanol to form a paste. They the rare earth metals is preferred. For examare then milled in a hard porcelain ball mill with pie, the addition to the zinc-beryllium silicate relatively light pebbles, preferably of to base of 0.7% of manganese dioxide and 0.4% of size, with the mill running rather slowly, so that Samarium oxide (SnmOa) produces a very bril- 45 no considerable shock will be given to the partlllant and quite white light. Very white and brilcles. The material may be milled for 20 to 22 liant illumination was produced by adding to the hours. The mixture is then dried and carefully beryllium-zinc silicate base, 1% of manganese brushed through a 200 mesh screen and is then dioxide and 0.4% to 0.5% of either samarium packed into a crucible for heat treating. This or neodymium oxide (NdzOs). The use of 0.7% 50 packing should be such as not to pack the mateof manganese dioxide with 0.4% of the samarium rial too tightly, or else hard sintered particles will or neodymium oxides is slightly whiter than the result. The powder is then heat treated as deprevious example, but it is not quite so brilliant. scribed in my copending application Serial 190,- The use of 0.6% of samarium oxide with 0.7%

880, in such manner that there is no slntering or of manganese dioxide is not quite so white or 66 bright. Less amountsthan0.4% oftherareeartll metaLgenerally give less favorable results when compared to the 0.4% to 0.5% range.

Other rare earths may be substituted for the examples given. For example, an extremely bright white light. only slightly deficient in red is produced by the use of 0.7% manganese dioxide and 0.5% lanthanum oxide in combination with the zinc beryllium base.

Many of the powders here described have a considerably greater illumination eillciency than tungsten lights. For example, the lanthanummanagnese compound described incorporating 0.7% manganese dioxide and 0.5% lanthanum oxide, used in a glass tube with half the glass covered by the powder, produces on a light meter. approximately ten times the light per unit current compared to the base tungsten lights available on the market.

The powder produced in accordance with this process is in the form of small unbroken crystals about 95% of which are less than two microns insize. About 50% of the crystals are from onequarter to one micron in size.

This application is a continuation in part of my copending application Serial Number 202,804 flied April 18, 1938.

The foregoing detailed description has been mven for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

I claim:

1. A fluorescent powder consisting essentially of unground crystals of a size of the order of one micron in diameter of zinc beryllium silicate. the crystals containing a minor proportion of an activator.

2. Aiiuorescent powder-comprislngxincberybliumsilicateintheformofunsroundcrystals substantiallyalllessthantwomicronsinsixeand a pair of activators. one of the activators being arare earthmetal.

I A fluorescent element comprising unfused unground minute particles substantially all less than two microns in siaeofaincberyllium silicate containingasmallproportionoflnlnganese.

4. A fluorescent material comprising zinc m beryllium silicate in the form of unground crystals substantially all less than two microns in size containing approximately 0.4% to 1.0% manganese oxide and approximately 0.4% to 0.5% of a rare earth metal.

5.Amaterialassetiorthinclaim4inwhich u the rare earth metal is samarium.

6. Amaterialassetforthinclalm4inwhlch the rare earth metal is lanthanum.

l.Amaterialassetforthinclaim4invvhich the rare earth metal is neodymium.

8. A fluorescent material comprising in the form of Imsround crystals substantially all less than two microns in size zinc beryllium silicate containing approximately 0.7% to 1.0% manganese oxide and approximately 0.4% to 0.5% of i a rare earth metal.

9. A fluorescent material comprising minute crystals of zinc beryllium silicate containing approximately 0.4% to approximately 0.4 to 0.5 of samarium.

10. A fluorescent material comprising minute crystals of zinc beryllium silicate containing approximately 0.4% to 1% of manganese oxide and approximately 0.4% to 0.5% of neodymium.

cam. Pram Patent No. 2,175,100.

CARL PFANSTIEHL October 17, 1959.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 16, for the word "portions" read proportions; page 2, secand column, line 21 cla1m8, strike out "zinc beryllium silicate" and insort the same after "comprising", line 22, same claim; line 51, claim 9, for "Othto 0.5" read 0.1. .1 to 0.5%; and that the said Letters Patent should be read with this correction therein that 'the same may conform to the record of the case. in the Patent Office.

Signed and sealed this 19th day oi December, A. D. 1959.

Henry Van Ars'dale Acting Commissioner of ratents.

1% of manganese oxide and u bright. Less amountsthan0.4% oftherareeartll metaLgenerally give less favorable results when compared to the 0.4% to 0.5% range.

Other rare earths may be substituted for the examples given. For example, an extremely bright white light. only slightly deficient in red is produced by the use of 0.7% manganese dioxide and 0.5% lanthanum oxide in combination with the zinc beryllium base.

Many of the powders here described have a considerably greater illumination eillciency than tungsten lights. For example, the lanthanummanagnese compound described incorporating 0.7% manganese dioxide and 0.5% lanthanum oxide, used in a glass tube with half the glass covered by the powder, produces on a light meter. approximately ten times the light per unit current compared to the base tungsten lights available on the market.

The powder produced in accordance with this process is in the form of small unbroken crystals about 95% of which are less than two microns insize. About 50% of the crystals are from onequarter to one micron in size.

This application is a continuation in part of my copending application Serial Number 202,804 flied April 18, 1938.

The foregoing detailed description has been mven for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

I claim:

1. A fluorescent powder consisting essentially of unground crystals of a size of the order of one micron in diameter of zinc beryllium silicate. the crystals containing a minor proportion of an activator.

2. Aiiuorescent powder-comprislngxincberybliumsilicateintheformofunsroundcrystals substantiallyalllessthantwomicronsinsixeand a pair of activators. one of the activators being arare earthmetal.

I A fluorescent element comprising unfused unground minute particles substantially all less than two microns in siaeofaincberyllium silicate containingasmallproportionoflnlnganese.

4. A fluorescent material comprising zinc m beryllium silicate in the form of unground crystals substantially all less than two microns in size containing approximately 0.4% to 1.0% manganese oxide and approximately 0.4% to 0.5% of a rare earth metal.

5.Amaterialassetiorthinclaim4inwhich u the rare earth metal is samarium.

6. Amaterialassetforthinclalm4inwhlch the rare earth metal is lanthanum.

l.Amaterialassetforthinclaim4invvhich the rare earth metal is neodymium.

8. A fluorescent material comprising in the form of Imsround crystals substantially all less than two microns in size zinc beryllium silicate containing approximately 0.7% to 1.0% manganese oxide and approximately 0.4% to 0.5% of i a rare earth metal.

9. A fluorescent material comprising minute crystals of zinc beryllium silicate containing approximately 0.4% to approximately 0.4 to 0.5 of samarium.

10. A fluorescent material comprising minute crystals of zinc beryllium silicate containing approximately 0.4% to 1% of manganese oxide and approximately 0.4% to 0.5% of neodymium.

cam. Pram Patent No. 2,175,100.

CARL PFANSTIEHL October 17, 1959.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 16, for the word "portions" read proportions; page 2, secand column, line 21 cla1m8, strike out "zinc beryllium silicate" and insort the same after "comprising", line 22, same claim; line 51, claim 9, for "Othto 0.5" read 0.1. .1 to 0.5%; and that the said Letters Patent should be read with this correction therein that 'the same may conform to the record of the case. in the Patent Office.

Signed and sealed this 19th day oi December, A. D. 1959.

Henry Van Ars'dale Acting Commissioner of ratents.

1% of manganese oxide and u 

